#!/bin/sh
#  Move a git-based directory with all of its history into a subdirectory,
#  in preparation for merging as a subtree.
#

usage="Usage: $0 [-h|--help] [subtree]\n
    Move files and git history into a subtree.  If no name is given on the\n
    command line, the subtree will have the same name as the current directory.
"

if [ "-h" = "$1" ] || [ "--help" = "$1" ]; then
    echo $usage
    exit 0;
elif [ ! -d .git ] ; then
    echo "not a git repository"
    echo $usage
    exit 1;
fi

if [ ! -z "$1" ]; then
    dir="$1"
else
    pwd=`pwd`
    dir=`basename ${pwd}`
fi

echo "moving repo into subtree $dir"

git add .
git commit --allow-empty -m "moving repo into subtree $dir"


#  http://stackoverflow.com/questions/4042816/how-can-i-rewrite-history-so-that-all-files-except-the-ones-i-already-moved-ar
git filter-branch --prune-empty --tree-filter "
    if [ ! -e $dir ]; then mkdir -p $dir;
	    git ls-tree --name-only \$GIT_COMMIT | xargs -I files mv files $dir;
    fi"